A SINGLE-PARTICLE MODEL OF CERENKOV FEL WITH CYLINDRICAL WAVEGUIDES

A single-particle model is used to investigate Cerenkov free electron laser with annular relativistic electron beams contained in dielectric-loaded cylindrical waveguides. Frequency tunabiliy is discussed and growth rate is derived. The threshold current for overcoming the cavity losses is calculated. Results show that the gap between the beam and the dielectric can degrade the beam-mode coupling .The growth rate for an annular beam may be higher than that for a solid beam.